Malaria protection due to sickle haemoglobin depends on parasite genotype

Host genetic factors can confer resistance against malaria¹, raising the question of whether this has led to evolutionary adaptation of parasite populations. Here we searched for association between candidate host and parasite genetic variants in 3,346 Gambian and Kenyan children with severe malaria caused by Plasmodium falciparum. We identified a strong association between sickle haemoglobin (HbS) in the host and three regions of the parasite genome, which is not explained by population structure or other covariates, and which is replicated in additional samples. The HbS-associated alleles include nonsynonymous variants in the gene for the acyl-CoA synthetase family member^2–4PfACS8 on chromosome 2, in a second region of chromosome 2, and in a region containing structural variation on chromosome 11. The alleles are in strong linkage disequilibrium and have frequencies that covary with the frequency of HbS across populations, in particular being much more common in Africa than other parts of the world. The estimated protective effect of HbS against severe malaria, as determined by comparison of cases with population controls, varies greatly according to the parasite genotype at these three loci. These findings open up a new avenue of enquiry into the biological and epidemiological significance of the HbS-associated polymorphisms in the parasite genome and the evolutionary forces that have led to their high frequency and strong linkage disequilibrium in African P. falciparum populations.

A strong association has been found between three regions of the Plasmodium falciparum genome and sickle haemoglobin in children with severe malaria, suggesting parasites have adapted to overcome natural host immunity.

Hepatitis B virus preS2Δ38-55 variants: A newly identified risk factor for hepatocellular carcinoma

BACKGROUND & AIMS

Although HBV is a major cause of death in Africa, its genetic variability has been poorly documented. This study aimed to address whether HBV genotype and surface gene variants are associated with HBV-related liver disease in The Gambia.

METHODS

We conducted a case-control study nested in the Prevention of Liver Fibrosis and Cancer in Africa programme. Consecutive treatment-naive patients with chronic HBV infection and detectable viral load were recruited: 211 controls with no significant liver disease and 91 cases (56 cirrhosis and 35 HCC cases). HBV genotypes and surface gene variants were determined by Sanger sequencing or next-generation sequencing (NGS) in serum DNA. Aflatoxin B1 (AFB1)-specific codon 249 TP53 mutation was determined by NGS in circulating cell-free plasma DNA.

RESULTS

In phylogenetic analysis, 85% of individuals carried HBV genotype E, 14% genotype A, and 1% A/E recombinant viruses. Surface gene variants were more frequently observed in cases (43% and 57% in cirrhosis and HCC cases, respectively) than controls (25%; p <0.001), with preS2 deletions between nucleotides 38-55 (preS2Δ38-55) being the main genetic variant detected. In multivariable analysis, HBeAg seropositivity, low HBsAg levels, and HDV seropositivity were significantly associated with cirrhosis and HCC, whilst older age, higher viral load, genotype A, preS2Δ38-55, and AFB1 exposure were only associated with HCC. There was a multiplicative joint effect of preS2Δ38-55 variants with HBeAg seropositivity (odds ratio [OR] 43.1 [10.4-177.7]), high viral load >2,000 IU/ml (OR 22.7 [8.0-64.9]), HBsAg levels <10,000 IU/ml (OR 19.0 [5.5-65.3]), and AFB1 exposure (OR 29.3 [3.7-230.4]) on HCC risk.

CONCLUSIONS

This study identified a hotspot for HBV preS2 deletions as a strong independent factor for HCC in The Gambia, with HBV genotypes and AFB1 exposure contributing to the high liver cancer risk.

LAY SUMMARY

Although HBV-related liver disease is highly prevalent in sub-Saharan Africa, the associated virological characteristics are poorly studied. Using clinical data from African patients chronically infected with HBV, an assessment of the virological variability (genotypes and mutations) and exposure to AFB1, a toxin often contaminating food, was carried out. Our results show that HBV genotypes, the presence of a highly prevalent mutant form of HBV, and AFB1 exposure contribute to the high liver cancer risk in this population.

The PRECISE (PREgnancy Care Integrating translational Science, Everywhere) Network's first protocol: deep phenotyping in three sub-Saharan African countries

BACKGROUND

The PRECISE (PREgnancy Care Integrating translational Science, Everywhere) Network is a new and broadly-based group of research scientists and health advocates based in the UK, Africa and North America.

METHODS

This paper describes the protocol that underpins the clinical research activity of the Network, so that the investigators, and broader global health community, can have access to 'deep phenotyping' (social determinants of health, demographic and clinical parameters, placental biology and agnostic discovery biology) of women as they advance through pregnancy to the end of the puerperium, whether those pregnancies have normal outcomes or are complicated by one/more of the placental disorders of pregnancy (pregnancy hypertension, fetal growth restriction and stillbirth). Our clinical sites are in The Gambia (Farafenni), Kenya (Kilifi County), and Mozambique (Maputo Province). In each country, 50 non-pregnant women of reproductive age will be recruited each month for 1 year, to provide a final national sample size of 600; these women will provide culturally-, ethnically-, seasonally- and spatially-relevant control data with which to compare women with normal and complicated pregnancies. Between the three countries we will recruit ≈10,000 unselected pregnant women over 2 years. An estimated 1500 women will experience one/more placental complications over the same epoch. Importantly, as we will have accurate gestational age dating using the TraCer device, we will be able to discriminate between fetal growth restriction and preterm birth. Recruitment and follow-up will be primarily facility-based and will include women booking for antenatal care, subsequent visits in the third trimester, at time-of-disease, when relevant, during/immediately after birth and 6 weeks after birth.

CONCLUSIONS

To accelerate progress towards the women's and children's health-relevant Sustainable Development Goals, we need to understand how a variety of social, chronic disease, biomarker and pregnancy-specific determinants health interact to result in either a resilient or a compromised pregnancy for either mother or fetus/newborn, or both. This protocol has been designed to create such a depth of understanding. We are seeking funding to maintain the cohort to better understand the implications of pregnancy complications for both maternal and child health.

First trimester use of artemisinin-based combination therapy and the risk of low birth weight and small for gestational age

Background

While there is increasing evidence on the safety of artemisinin-based combination therapy (ACT) for the case management of malaria in early pregnancy, little is known about the association between exposure to ACT during the first trimester and the effect on fetal growth.

Methods

Data were analysed from prospective studies of pregnant women enrolled in Mozambique, Burkina Faso and Kenya designed to determine the association between anti-malarial drug exposure in the first trimester and pregnancy outcomes, including low birth weight (LBW) and small for gestational age (SGA). Exposure to anti-malarial drugs was ascertained retrospectively by record linkage using a combination of data collected from antenatal and adult outpatient clinic registries, prescription records and self-reported medication usage by the women. Site-level data synthesis (fixed effects and random effects) was conducted as well as individual-level analysis (fixed effects by site).

Results

Overall, 1915 newborns were included with 92 and 26 exposed to ACT (artemether–lumefantrine) and quinine, respectively. In Burkina Faso, Mozambique and Kenya at recruitment, the mean age (standard deviation) was 27.1 (6.6), 24.2 (6.2) and 25.7 (6.5) years, and the mean gestational age was 24.0 (6.2), 21.2 (5.7) and 17.9 (10.2) weeks, respectively. The LBW prevalence among newborns born to women exposed to ACT and quinine (QNN) during the first trimester was 10/92 (10.9%) and 7/26 (26.9%), respectively, compared to 9.5% (171/1797) among women unexposed to any anti-malarials during pregnancy. Compared to those unexposed to anti-malarials, ACT and QNN exposed women had the pooled LBW prevalence ratio (PR) of 1.13 (95% confidence interval (CI) 0.62–2.05, p-value 0.700) and 2.03 (95% CI 1.09–3.78, p-value 0.027), respectively. Compared to those unexposed to anti-malarials ACT and QNN-exposed women had the pooled SGA PR of 0.85 (95% CI 0.50–1.44, p-value 0.543) and 1.41 (95% CI 0.71–2.77, p-value 0.322), respectively. Whereas compared to ACT-exposed, the QNN-exposed had a PR of 2.14 (95% CI 0.78–5.89, p-value 0.142) for LBW and 8.60 (95% CI 1.29–57.6, p-value 0.027) for SGA. The level of between sites heterogeneity was moderate to high.

Conclusion

ACT exposure during the first trimester was not associated with an increased occurrence of LBW or SGA. However, the data suggest a higher prevalence of LBW and SGA for children born to QNN-exposed pregnancies. The findings support the use of ACT (artemether–lumefantrine) for the treatment of uncomplicated malaria during the first trimester of pregnancy.

A survey of Anopheles species composition and insecticide resistance on the island of Bubaque, Bijagos Archipelago, Guinea-Bissau

Background

Bubaque is the most populous island of the Bijagos archipelago, a group of malaria-endemic islands situated off the coast of Guinea-Bissau, West Africa. Malaria vector control on Bubaque relies almost exclusively on the use of long-lasting insecticidal nets (LLINs). However, there is little information on local vector bionomics and insecticide resistance.

Methods

A survey of mosquito species composition was performed at the onset of the wet season (June/July) and the beginning of the dry season (November/December). Sampling was performed using indoor adult light-traps and larval dipping. Anopheles mosquitoes were identified to species level and assessed for kdr allele frequency by TaqMan PCR. Females were analysed for sporozoite positivity by CSP-ELISA. Resistance to permethrin and α-cypermethrin was measured using the CDC-bottle bioassay incorporating the synergist piperonyl-butoxide.

Results

Several Anopheles species were found on the island, all belonging to the Anopheles gambiae sensu lato (s.l.) complex, including An. gambiae sensu stricto, Anopheles coluzzii, Anopheles melas, and An. gambiae/An. coluzzii hybrids. Endophagic Anopheles species composition and abundance showed strong seasonal variation, with a majority of An. gambiae (50% of adults collected) caught in June/July, while An. melas was dominant in November/December (83.9% of adults collected). Anopheles gambiae had the highest sporozoite rate in both seasons, with infection rates of 13.9% and 20% in June/July and November/December, respectively. Moderate frequencies of the West African kdr allele were found in An. gambiae (36%), An. coluzzii (35%), An. gambiae/An. coluzzii hybrids (42%). Bioassays suggest moderate resistance to α-cypermethrin, but full susceptibility to permethrin.

Conclusions

The island of Bubaque maintained an An. gambiae s.l. population in both June/July and November/December. Anopheles gambiae was the primary vector at the onset of the wet season, while An. melas is likely to be responsible for most dry season transmission. There was moderate kdr allele frequency and synergist assays suggest likely metabolic resistance, which could reduce the efficacy of LLINs. Future control of malaria on the islands should consider the seasonal shift in mosquito species, and should employ continuous monitoring for insecticide resistance.

In vivo/ex vivo efficacy of artemether-lumefantrine and artesunate-amodiaquine as first-line treatment for uncomplicated falciparum malaria in children: an open label randomized controlled trial in Burkina Faso

BACKGROUND

Artemisinin-based combination therapy (ACT) is recommended to improve malaria treatment efficacy and limit drug-resistant parasites selection in malaria endemic areas. 5 years after they were adopted, the efficacy and safety of artemether-lumefantrine (AL) and artesunate-amodiaquine (ASAQ), the first-line treatments for uncomplicated malaria were assessed in Burkina Faso.

METHODS

In total, 440 children with uncomplicated Plasmodium falciparum malaria were randomized to receive either AL or ASAQ for 3 days and were followed up weekly for 42 days. Blood samples were collected to investigate the ex vivo susceptibility of P. falciparum isolates to lumefantrine, dihydroartemisinin (the active metabolite of artemisinin derivatives) and monodesethylamodiaquine (the active metabolite of amodiaquine). The modified isotopic micro test technique was used to determine the 50% inhibitory concentration (IC50) values. Primary endpoints were the risks of treatment failure at days 42.

RESULTS

Out of the 440 patients enrolled, 420 (95.5%) completed the 42 days follow up. The results showed a significantly higher PCR unadjusted cure rate in ASAQ arm (71.0%) than that in the AL arm (49.8%) on day 42, and this trend was similar after correction by PCR, with ASAQ performing better (98.1%) than AL (91.1%). Overall adverse events incidence was low and not significantly different between the two treatment arms. Ex vivo results showed that 6.4% P. falciparum isolates were resistant to monodesthylamodiaquine. The coupled in vivo/ex vivo analysis showed increased IC50 values for lumefantrine and monodesethylamodiaquine at day of recurrent parasitaemia compared to baseline values while for artesunate, IC50 values remained stable at baseline and after treatment failure (p > 0.05).

CONCLUSION

These findings provide substantial evidence that AL and ASAQ are highly efficacious for the treatment of uncomplicated malaria in children in Burkina Faso. However, the result of P. falciparum susceptibility to the partner drugs advocates the need to regularly replicate such surveillance studies. This would be particularly indicated when amodiaquine is associated in seasonal malaria chemoprophylaxis (SMC) mass drug administration in children under 5 years in Burkina Faso. Trial registration clinicaltrials, NCT00808951. Registered 05 December 2008,https://clinicaltrials.gov/ct2/show/NCT00808951?cond=NCT00808951&rank=1.

Bead-based assays to simultaneously detect multiple human inherited blood disorders associated with malaria

BACKGROUND

Glucose-6-phosphate dehydrogenase deficiency (G6PDd), haemoglobin C (HbC) and S (HbS) are inherited blood disorders (IBD) common in populations in malaria endemic areas. All are associated to some degree with protection against clinical malaria whilst additionally G6PDd is associated with haemolysis following treatment with 8-aminoquinolines. Measuring the prevalence of these inherited blood disorders in affected populations can improve understanding of disease epidemiology. Current methodologies in epidemiological studies commonly rely on individual target amplification and visualization; here a method is presented to simultaneously detect the polymorphisms and that can be expanded to include other single nucleotide polymorphisms (SNPs) of interest.

METHODS

Human DNA from whole blood samples was amplified in a novel, multiplex PCR reaction and extended with SNP-specific probes in an allele specific primer extension (ASPE) to simultaneously detect four epidemiologically important human markers including G6PD SNPs (G202A and A376G) and common haemoglobin mutations (HbS and HbC). The products were hybridized to magnetic beads and the median fluorescence intensity (MFI) was read on MAGPIX® (Luminex corp.). Genotyping data was compared to phenotypical data generated by flow cytometry and to established genotyping methods.

RESULTS

Seventy-five samples from Burkina Faso (n = 75/78, 96.2%) and 58 samples from The Gambia (n = 58/61, 95.1%) had a G6PD and a HBB genotype successfully assigned by the bead-based assay. Flow cytometry data available for n = 61 samples further supported the concordance between % G6PD normal/deficient cells and genotype.

CONCLUSIONS

The bead based assay compares well to alternative measures of genotyping and phenotyping for G6PD. The screening is high throughput, adaptable to inclusion of multiple targets of interest and easily standardized.

The role of leadership in people-centred health systems: a sub-national study in The Gambia

Recently, increasing attention has been given to behavioural and relational aspects of the people who both define and shape health systems, placing them at the core. A growing refrain includes the assertion that important decisions determining health system performance, including agenda setting, policy formulation and policy implementation, are made by people. Within this actor-oriented approach, good leadership has been identified as a key contributing factor in health systems strengthening. However, leadership remains ill-defined and under-researched, especially in resource-limited settings, and understanding the links between leadership and health outcomes remains a challenge. We explore the concept and practice of healthcare leadership at sub-national level in a low-income country setting, using a people-centric research methodology. In June and July 2013, 15 in-depth interviews were conducted with key informants in formal healthcare leadership roles across urban, peri-urban and rural settings of The Gambia, West Africa. Participants included the entire spectrum of Regional Health Team (RHT) Directors and Chief Executive Officers of all government hospitals, as well as one clinical officer-in-charge in a secondary-level major health centre. We found reference to several important aspects of, and approaches to, leadership, including (i) setting a clear vision; (ii) engendering shared leadership; and (iii) paying attention to human relations in management. Participants described attending to constituencies in government, international development agencies and civil society, as well as to the populations they serve. By illuminating the multi-polar networks within which these leaders are embedded, and through which they operate, we provide insight into the complex 'organizational ecology' of the Gambian health system. There is a need to further research and develop healthcare leadership across all levels, within various political, socio-economic and cultural contexts, in order to better work with a range of health actors and to engage them in identifying and acting upon opportunities for health systems strengthening.

Detection, characterization, and enrollment of donors of Ebola convalescent plasma in Sierra Leone

BACKGROUND

Passive therapy with convalescent plasma provides an early opportunity to intervene in Ebola virus disease (EVD). Methods for field screening and selection of potential donors and quantifying plasma antibody are needed.

STUDY DESIGN AND METHODS

Recombinant Ebola virus glycoprotein (EBOV GP) was formatted into immunoglobulin G‐capture, competitive, and double‐antigen bridging enzyme immunoassays (EIAs). EVD survivors in Freetown, Sierra Leone, were recruited as potential plasma donors and assessed locally using sera alone and/or paired sera and oral fluids (ORFs). Uninfected controls comprised unexposed Gambians and communities in Western Area, Sierra Leone. Antibody neutralization in selected sera was measured retrospectively in a pseudotype virus assay.

RESULTS

A total of 115 potential donors were considered for enrollment: 110 plasma samples were concordantly reactive in the three EIAs; three were concordantly unreactive and two were reactive in two of three EIAs (98.2% agreement; 95% confidence interval [CI], 93.9%‐99.8%). In 88 donors with paired ORF and plasma, G‐capture EIA reactivity correlated well in the two analytes (R² = 0.795). Plasma and ORF from 44 Gambians were unreactive. ORF samples from 338 of 339 unexposed Western Area community controls were unreactive (specificity, 99.7%; 95% CI, 98.4%‐99.7%); ORF samples from 113 of 116 Kerry Town EVD survivors were reactive (sensitivity, 97.4%; 95% CI, 92.5%‐99.5%). Strong reactivity in G‐capture and/or competitive EIAs identified donors with high plasma EBOV GP antibody levels in the double‐antigen bridging assay, correlating with high levels of neutralizing antibody.

CONCLUSIONS

In‐field testing can qualify convalescent donors for providing high‐titer antibody.

Interleukin-10 and soluble tumor necrosis factor receptor II are potential biomarkers of Plasmodium falciparum infections in pregnant women: a case-control study from Nanoro, Burkina Faso

Background

Diagnosis of malaria in pregnancy is problematic due to the low sensitivity of conventional diagnostic tests (rapid diagnostic test and microscopy), which is exacerbated due to low peripheral parasite densities, and lack of clinical symptoms. In this study, six potential biomarkers to support malaria diagnosis in pregnancy were evaluated.

Methods

Blood samples were collected from pregnant women at antenatal clinic visits and at delivery. Microscopy and real-time PCR were performed for malaria diagnosis and biomarker analyses were performed by ELISA (interleukin 10, IL-10; tumor necrosis factor-α, TNF-α; soluble tumor necrosis factor receptor II, sTNF-RII; soluble fms-like tyrosine kinase 1, sFlt-1; leptin and apolipoprotein B, Apo-B). A placental biopsy was collected at delivery to determine placental malaria.

Results

IL-10 and sTNF-RII were significantly higher at all time-points in malaria-infected women (p < 0.001). Both markers were also positively associated with parasite density (p < 0.001 and p = 0.003 for IL-10 and sTNF-RII respectively). IL-10 levels at delivery, but not during pregnancy, were negatively associated with birth weight. A prediction model was created using IL-10 and sTNF-RII cut-off points. For primigravidae the model had a sensitivity of 88.9% (95%CI 45.7–98.7%) and specificity of 83.3% (95% CI 57.1–94.9%) for diagnosing malaria during pregnancy. For secundi- and multigravidae the sensitivity (81.8% and 56.5% respectively) was lower, while specificity (100.0% and 94.3% respectively) was relatively high. Sub-microscopic infections were detected in 2 out of 3 secundi- and 5 out of 12 multigravidae.

Conclusions

The combination of biomarkers IL-10 and sTNF-RII have the potential to support malaria diagnosis in pregnancy. Additional markers may be needed to increase sensitivity and specificity, this is of particular importance in populations with sub-microscopic infections or in whom other inflammatory diseases are prevalent.

Electronic supplementary material

The online version of this article (10.1186/s40364-017-0114-7) contains supplementary material, which is available to authorized users.

Increase in the prevalence of mutations associated with sulfadoxine-pyrimethamine resistance in Plasmodium falciparum isolates collected from early to late pregnancy in Nanoro, Burkina Faso

BACKGROUND

Pregnant women are a high-risk group for Plasmodium falciparum infections, which may result in maternal anaemia and low birth weight newborns, among other adverse birth outcomes. Intermittent preventive treatment with sulfadoxine-pyrimethamine during pregnancy (IPTp-SP) is widely implemented to prevent these negative effects of malaria. However, resistance against SP by P. falciparum may decrease efficacy of IPTp-SP. Combinations of point mutations in the dhps (codons A437, K540) and dhfr genes (codons N51, C59, S108) of P. falciparum are associated with SP resistance. In this study the prevalence of SP resistance mutations was determined among P. falciparum found in pregnant women and the general population (GP) from Nanoro, Burkina Faso and the association of IPTp-SP dosing and other variables with mutations was studied.

METHODS

Blood spots on filter papers were collected from pregnant women at their first antenatal care visit (ANC booking) and at delivery, from an ongoing trial and from the GP in a cross-sectional survey. The dhps and dhfr genes were amplified by nested PCR and products were sequenced to identify mutations conferring resistance (ANC booking, n = 400; delivery, n = 223; GP, n = 400). Prevalence was estimated with generalized estimating equations and for multivariate analyses mixed effects logistic regression was used.

RESULTS

The prevalence of the triple dhfr mutation was high, and significantly higher in the GP and at delivery than at ANC booking, but it did not affect birth weight. Furthermore, quintuple mutations (triple dhfr and double dhps mutations) were found for the first time in Burkina Faso. IPTp-SP did not significantly affect the occurrence of any of the mutations, but high transmission season was associated with increased mutation prevalence in delivery samples. It is unclear why the prevalence of mutations was higher in the GP than in pregnant women at ANC booking.

CONCLUSION

The high number of mutants and the presence of quintuple mutants in Burkina Faso confirm concerns about the efficacy of IPTp-SP in the near future. Other drug combinations to tackle malaria in pregnancy should, therefore, be explored. An increase in mutation prevalence due to IPTp-SP dosing could not be confirmed.

Maternal Malaria and Malnutrition (M3) initiative, a pooled birth cohort of 13 pregnancy studies in Africa and the Western Pacific

PURPOSE

The Maternal Malaria and Malnutrition (M3) initiative has pooled together 13 studies with the hope of improving understanding of malaria-nutrition interactions during pregnancy and to foster collaboration between nutritionists and malariologists.

PARTICIPANTS

Data were pooled on 14 635 singleton, live birth pregnancies from women who had participated in 1 of 13 pregnancy studies. The 13 studies cover 8 countries in Africa and Papua New Guinea in the Western Pacific conducted from 1996 to 2015.

FINDINGS TO DATE

Data are available at the time of antenatal enrolment of women into their respective parent study and at delivery. The data set comprises essential data such as malaria infection status, anthropometric assessments of maternal nutritional status, presence of anaemia and birth weight, as well as additional variables such gestational age at delivery for a subset of women. Participating studies are described in detail with regard to setting and primary outcome measures, and summarised data are available from each contributing cohort.

FUTURE PLANS

This pooled birth cohort is the largest pregnancy data set to date to permit a more definite evaluation of the impact of plausible interactions between poor nutritional status and malaria infection in pregnant women on fetal growth and gestational length. Given the current comparative lack of large pregnancy cohorts in malaria-endemic settings, compilation of suitable pregnancy cohorts is likely to provide adequate statistical power to assess malaria-nutrition interactions, and could point towards settings where such interactions are most relevant. The M3 cohort may thus help to identify pregnant women at high risk of adverse outcomes who may benefit from tailored intensive antenatal care including nutritional supplements and alternative or intensified malaria prevention regimens, and the settings in which these interventions would be most effective.

A tuberculosis nationwide prevalence survey in Gambia, 2012

Objective

To estimate the population prevalence of active pulmonary tuberculosis in Gambia.

Methods

Between December 2011 and January 2013, people aged ≥ 15 years participating in a nationwide, multistage cluster survey were screened for active pulmonary tuberculosis with chest radiography and for tuberculosis symptoms. For diagnostic confirmation, sputum samples were collected from those whose screening were positive and subjected to fluorescence microscopy and liquid tuberculosis cultures. Multiple imputation and inverse probability weighting were used to estimate tuberculosis prevalence.

Findings

Of 100 678 people enumerated, 55 832 were eligible to participate and 43 100 (77.2%) of those participated. A majority of participants (42 942; 99.6%) were successfully screened for symptoms and by chest X-ray. Only 5948 (13.8%) were eligible for sputum examination, yielding 43 bacteriologically confirmed, 28 definite smear-positive and six probable smear-positive tuberculosis cases. Chest X-ray identified more tuberculosis cases (58/69) than did symptoms alone (43/71). The estimated prevalence of smear-positive and bacteriologically confirmed pulmonary tuberculosis were 90 (95% confidence interval, CI: 53–127) and 212 (95% CI: 152–272) per 100 000 population, respectively. Tuberculosis prevalence was higher in males (333; 95% CI: 233–433) and in the 35–54 year age group (355; 95% CI: 219–490).

Conclusion

The burden of tuberculosis remains high in Gambia but lower than earlier estimates of 490 per 100 000 population in 2010. Less than half of all cases would have been identified based on smear microscopy results alone. Successful control efforts will require interventions targeting men, increased access to radiography and more accurate, rapid diagnostic tests.

Assessment of the safety of antimalarial drug use during early pregnancy (ASAP): protocol for a multicenter prospective cohort study in Burkina Faso, Kenya and Mozambique

Background

A major unresolved safety concern for malaria case management is the use of artemisinin combination therapies (ACTs) in the first trimester of pregnancy. There is a need for human data to inform policy makers and treatment guidelines on the safety of artemisinin combination therapies (ACT) when used during early pregnancy.

Methods

The overall goal of this paper is to describe the methods and implementation of a study aimed at developing surveillance systems for identifying exposures to antimalarials during early pregnancy and for monitoring pregnancy outcomes using health and demographic surveillance platforms.

This was a multi-center prospective observational cohort study involving women at health and demographic surveillance sites in three countries in Africa: Burkina Faso, Kenya and Mozambique [(ClinicalTrials.gov Identifier: NCT01232530)]. The study was designed to identify pregnant women with artemisinin exposure in the first trimester and compare them to: 1) pregnant women without malaria, 2) pregnant women treated for malaria, but exposed to other antimalarials, and 3) pregnant women with malaria and treated with artemisinins in the 2nd or 3rd trimesters from the same settings. Pregnant women were recruited through community-based surveys and attendance at health facilities, including antenatal care clinics and followed until delivery. Data from the three sites will be pooled for analysis at the end of the study. Results are forthcoming.

Discussion

Despite few limitations, the methods described here are relevant to the development of sustainable pharmacovigilance systems for drugs used by pregnant women in the tropics using health and demographic surveillance sites to prospectively ascertain drug safety in early pregnancy.

Trial registration

NCT01232530

Electronic supplementary material

The online version of this article (doi:10.1186/s12978-015-0101-0) contains supplementary material, which is available to authorized users.

Characterizing Types of Human Mobility to Inform Differential and Targeted Malaria Elimination Strategies in Northeast Cambodia

Human population movements currently challenge malaria elimination in low transmission foci in the Greater Mekong Subregion. Using a mixed-methods design, combining ethnography (n = 410 interviews), malariometric data (n = 4996) and population surveys (n = 824 indigenous populations; n = 704 Khmer migrants) malaria vulnerability among different types of mobile populations was researched in the remote province of Ratanakiri, Cambodia. Different structural types of human mobility were identified, showing differential risk and vulnerability. Among local indigenous populations, access to malaria testing and treatment through the VMW-system and LLIN coverage was high but control strategies failed to account for forest farmers’ prolonged stays at forest farms/fields (61% during rainy season), increasing their exposure (p = 0.002). The Khmer migrants, with low acquired immunity, active on plantations and mines, represented a fundamentally different group not reached by LLIN-distribution campaigns since they were largely unregistered (79%) and unaware of the local VMW-system (95%) due to poor social integration. Khmer migrants therefore require control strategies including active detection, registration and immediate access to malaria prevention and control tools from which they are currently excluded. In conclusion, different types of mobility require different malaria elimination strategies. Targeting mobility without an in-depth understanding of malaria risk in each group challenges further progress towards elimination.

Clinical determinants of early parasitological response to ACTs in African patients with uncomplicated falciparum malaria: a literature review and meta-analysis of individual patient data

BACKGROUND

Artemisinin-resistant Plasmodium falciparum has emerged in the Greater Mekong sub-region and poses a major global public health threat. Slow parasite clearance is a key clinical manifestation of reduced susceptibility to artemisinin. This study was designed to establish the baseline values for clearance in patients from Sub-Saharan African countries with uncomplicated malaria treated with artemisinin-based combination therapies (ACTs).

METHODS

A literature review in PubMed was conducted in March 2013 to identify all prospective clinical trials (uncontrolled trials, controlled trials and randomized controlled trials), including ACTs conducted in Sub-Saharan Africa, between 1960 and 2012. Individual patient data from these studies were shared with the WorldWide Antimalarial Resistance Network (WWARN) and pooled using an a priori statistical analytical plan. Factors affecting early parasitological response were investigated using logistic regression with study sites fitted as a random effect. The risk of bias in included studies was evaluated based on study design, methodology and missing data.

RESULTS

In total, 29,493 patients from 84 clinical trials were included in the analysis, treated with artemether-lumefantrine (n = 13,664), artesunate-amodiaquine (n = 11,337) and dihydroartemisinin-piperaquine (n = 4,492). The overall parasite clearance rate was rapid. The parasite positivity rate (PPR) decreased from 59.7 % (95 % CI: 54.5-64.9) on day 1 to 6.7 % (95 % CI: 4.8-8.7) on day 2 and 0.9 % (95 % CI: 0.5-1.2) on day 3. The 95th percentile of observed day 3 PPR was 5.3 %. Independent risk factors predictive of day 3 positivity were: high baseline parasitaemia (adjusted odds ratio (AOR) = 1.16 (95 % CI: 1.08-1.25); per 2-fold increase in parasite density, P <0.001); fever (>37.5 °C) (AOR = 1.50 (95 % CI: 1.06-2.13), P = 0.022); severe anaemia (AOR = 2.04 (95 % CI: 1.21-3.44), P = 0.008); areas of low/moderate transmission setting (AOR = 2.71 (95 % CI: 1.38-5.36), P = 0.004); and treatment with the loose formulation of artesunate-amodiaquine (AOR = 2.27 (95 % CI: 1.14-4.51), P = 0.020, compared to dihydroartemisinin-piperaquine).

CONCLUSIONS

The three ACTs assessed in this analysis continue to achieve rapid early parasitological clearance across the sites assessed in Sub-Saharan Africa. A threshold of 5 % day 3 parasite positivity from a minimum sample size of 50 patients provides a more sensitive benchmark in Sub-Saharan Africa compared to the current recommended threshold of 10 % to trigger further investigation of artemisinin susceptibility.

Foul wind, spirits and witchcraft: illness conceptions and health-seeking behaviour for malaria in the Gambia

BACKGROUND

As the disease burden in the Gambia has reduced considerably over the last decade, heterogeneity in malaria transmission has become more marked, with infected but asymptomatic individuals maintaining the reservoir. The identification, timely diagnosis and treatment of malaria-infected individuals are crucial to further reduce or eliminate the human parasite reservoir. This ethnographic study focused on the relationship between local beliefs of the cause of malaria and treatment itineraries of suspected cases.

METHODS

An ethnographic qualitative study was conducted in twelve rural communities in the Upper River Region and the Central River Region in the Gambia. The data collection methods included in-depth interviews, participant observation, informal conversations, and focus group discussions.

RESULTS

While at first glance, the majority of people seek biomedical treatment for 'malaria', there are several constraints to seeking treatment at health centres. Certain folk illnesses, such as Jontinooje and Kajeje, translated and interpreted as 'malaria' by healthcare professionals, are often not considered to be malaria by local populations but rather as self-limiting febrile illnesses--consequently not leading to seeking care in the biomedical sector. Furthermore, respondents reported delaying treatment at a health centre while seeking financial resources, and consequently relying on herbal treatments. In addition, when malaria cases present symptoms, such as convulsions, hallucinations and/or loss of consciousness, the illness is often interpreted as having a supernatural aetiology, leading to diagnosis and treatment by traditional healers.

CONCLUSION

Although malaria diagnostics and treatment-seeking in the biomedical sector has been reported to be relatively high in the Gambia compared to other sub-Saharan African countries, local symptom interpretation and illness conceptions can delay or stop people from seeking timely biomedical treatment, which may contribute to maintaining a parasite reservoir of undiagnosed and untreated malaria patients.

Hematopoietic stem/progenitor cell sources to generate reticulocytes for Plasmodium vivax culture

The predilection of Plasmodium vivax (P. vivax) for reticulocytes is a major obstacle for its establishment in a long-term culture system, as this requires a continuous supply of large quantities of reticulocytes, representing only 1-2% of circulating red blood cells. We here compared the production of reticulocytes using an established in vitro culture system from three different sources of hematopoietic stem/progenitor cells (HSPC), i.e. umbilical cord blood (UCB), bone marrow (BM) and adult peripheral blood (PB). Compared to CD34+-enriched populations of PB and BM, CD34+-enriched populations of UCB produced the highest amount of reticulocytes that could be invaded by P. vivax. In addition, when CD34+-enriched cells were first expanded, a further extensive increase in reticulocytes was seen for UCB, to a lesser degree BM but not PB. As invasion by P. vivax was significantly better in reticulocytes generated in vitro, we also suggest that P. vivax may have a preference for invading immature reticulocytes, which should be confirmed in future studies.

Plasmodium falciparum clearance in clinical studies of artesunate-amodiaquine and comparator treatments in sub-Saharan Africa, 1999-2009

BACKGROUND

Artemisinin-based combination therapy (ACT) is the recommended first-line therapy for uncomplicated Plasmodium falciparum malaria worldwide but decreased artemisinin susceptibility, phenotypically characterized as slow parasite clearance time (PCT), has now been reported in Southeast Asia. This makes it all too important to measure the dynamics of parasite clearance in African patients treated with ACT over time, to understand trends and detect changes early enough to intervene

METHODS

Individual patient data from 27 clinical trials of artesunate-amodiaquine (ASAQ) vs comparators conducted between 1999 and 2009 were analysed for parasite clearance on modified intent-to-treat (ITT) basis.

RESULTS

Overall 15,017 patients treated for uncomplicated P. falciparum malaria at 44 sites in 20 sub-Saharan African countries were included in the analysis; 51% (n=7,660) vs 49% (n=7,357) were treated with ASAQ and comparator treatments, respectively. Seventy-seven per cent (77%) were children under six years of age. The proportion of the patients treated with ASAQ with persistent parasitaemia on Day 2 was 8.6%, and 1.5% on Day 3. Risk factor for not clearing parasites on Day 2 and Day 3 calculated by multivariate logistic regression with random effect on site and controlling for treatment were: high parasitaemia before treatment was (adjusted risk ratios (AOR) 2.12, 95% CI 1.91-2.35, AOR 2.43, 95% CI 1.98-3.00, respectively); non-ACT treatment (p=0.001, for all comparisons). Anaemia (p=0.001) was an additional factor for Day 2 and young age (p=0.005) for Day 3.In patients treated with ASAQ in studies who had complete parasitaemia data every 24 hours up to Day 3 and additionally Day 7, the parasite reduction ratio was 93.9% by Day 1 and 99.9% by Day 2. Using the median parasitaemia before treatment (p0=27,125 μL) and a fitted model, the predicted PCT (pPCT = 3.614*ln (p0) - 6.135, r(2) = 0.94) in ASAQ recipients was 31 hours.

CONCLUSION

Within the period covered by these studies, rapid Plasmodium falciparum clearance continues to be achieved in Sub-Saharan African patients treated with ACT, and in particular with ASAQ. The prediction formula for parasite clearance time could be a pragmatic tool for studies with binary outcomes and once-daily sampling, both for research and monitoring purposes.

Artemisinin resistance in rodent malaria--mutation in the AP2 adaptor μ-chain suggests involvement of endocytosis and membrane protein trafficking

BACKGROUND

The control of malaria, caused by Plasmodium falciparum, is hampered by the relentless evolution of drug resistance. Because artemisinin derivatives are now used in the most effective anti-malarial therapy, resistance to artemisinin would be catastrophic. Indeed, studies suggest that artemisinin resistance has already appeared in natural infections. Understanding the mechanisms of resistance would help to prolong the effective lifetime of these drugs. Genetic markers of resistance are therefore required urgently. Previously, a mutation in a de-ubiquitinating enzyme was shown to confer artemisinin resistance in the rodent malaria parasite Plasmodium chabaudi.

METHODS

Here, for a mutant P. chabaudi malaria parasite and its immediate progenitor, the in vivo artemisinin resistance phenotypes and the mutations arising using Illumina whole-genome re-sequencing were compared.

RESULTS

An increased artemisinin resistance phenotype is accompanied by one non-synonymous substitution. The mutated gene encodes the μ-chain of the AP2 adaptor complex, a component of the endocytic machinery. Homology models indicate that the mutated residue interacts with a cargo recognition sequence. In natural infections of the human malaria parasite P. falciparum, 12 polymorphisms (nine SNPs and three indels) were identified in the orthologous gene.

CONCLUSION

An increased artemisinin-resistant phenotype occurs along with a mutation in a functional element of the AP2 adaptor protein complex. This suggests that endocytosis and trafficking of membrane proteins may be involved, generating new insights into possible mechanisms of resistance. The genotypes of this adaptor protein can be evaluated for its role in artemisinin responses in human infections of P. falciparum.

[Determinants of adherence to treatment for uncomplicated malaria in northeastern Democratic Republic of Congo]

The purpose of this study was to identify the determinants of adherence to malaria<np pagenum="034"/> treatment (co-blistered AS-AQ) among health care providers, medicine sellers and patients in the northeastern region of the Democratic Republic of Congo. A cross-sectional study was carried out on health care providers, medicine sellers and patients in 13 health zones between March and June 2009. Only 69% of the cases of uncomplicated malaria were treated with AS-AQ, including 62.3% of cases treated using the correct dosages. The availability of AS-AQ, the intention to prescribe AS-AQ, longer consultations, providing explanations to patients, working in rural areas, training on the new policy, and the availability of treatment guidelines were found to be significantly associated with treatment adherence among health care providers. The limited availability of AS-AQ, the adverse effects of the treatment, the use of low-quality AS-AQ and the availability of cheap illegal antimalarial drugs were the main factors associated with non-adherence. Among patients, non-adherence was related to the perceived adverse effects of malaria treatment. The results suggest that improving the?accessibility and quality of AS-AQ and the quality of communication with patients, the provision of appropriate training to healthcare providers, the provision of treatment guidelines and appropriate supervision are needed to promote the use of AS-AQ.

Randomized controlled trial of 2 prenatal iron supplements: is there a dose-response relation with maternal hemoglobin?

BACKGROUND

The most appropriate dose of iron to prevent maternal anemia is still unclear.

OBJECTIVE

We assessed the dose-response relation between maternal hemoglobin and 2 prenatal iron supplements.

DESIGN

An intention-to-treat, double-blind, randomized controlled trial compared 30 mg Fe + folic acid and 13 other micronutrients (UNIMMAP; UNICEF/WHO/UNU multiple micronutrient supplement for pregnant and lactating women) with 60 mg Fe + folic acid (IFA) only in rural Burkina Faso. Home visitors directly observed tablet intake. Mixed-effects models were used for the data analysis.

RESULTS

At inclusion, 43.2% of the 1268 participants were anemic. On average, the hemoglobin concentration decreased over gestation by 0.019 g/dL (95% CI: 0.012, 0.025 g/dL) per week in the IFA and UNIMMAP groups. An increment in hemoglobin concentration per micronutrient tablet [β (±SE) = 0.006 ± 0.001 g/dL; P < 0001] was observed only in women who were anemic at inclusion, whereas a decrease was observed in the other mothers (-0.003 ± 0.001 g/dL; P = 0.002, P for interaction < 0.0001); the finding was similar in both the IFA and UNIMMAP groups. Women with baseline anemia achieved the same hemoglobin concentration (mean ± SD: 11.1 ± 0.64 g/dL) as their counterparts who received ±180 tablets of either UNIMMAP or IFA. Despite this, micronutrient intake did not significantly prevent anemia (51.0% in the third trimester). It was, however, a risk factor for hemoconcentration (odds ratio per tertile of tablet intake: 2.10; 95% CI: 1.12, 3.94), independently of supplement type or initial hemoglobin concentration.

CONCLUSIONS

UNIMMAP triggered the same hemoglobin dose response with half the amount of iron as provided by IFA treatment. The benefit of iron supplements in nonanemic women is unclear. Despite micronutrient supplementation, anemia remained highly prevalent during gestation, partly because of physiologic hemodilution. This trial was registered at clinicaltrials.gov as NCT00642408.

High risk of severe anaemia after chlorproguanil-dapsone+artesunate antimalarial treatment in patients with G6PD (A-) deficiency

BACKGROUND

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most common inherited human enzyme defect. This deficiency provides some protection from clinical malaria, but it can also cause haemolysis after administration of drugs with oxidant properties.

METHODS

The safety of chlorproguanil-dapsone+artesunate (CD+A) and amodiaquine+sulphadoxine-pyrimethamine (AQ+SP) for the treatment of uncomplicated P. falciparum malaria was evaluated according to G6PD deficiency in a secondary analysis of an open-label, randomized clinical trial. 702 children, treated with CD+A or AQ+SP and followed for 28 days after treatment were genotyped for G6PD A- deficiency.

FINDINGS

In the first 4 days following CD+A treatment, mean haematocrit declined on average 1.94% (95% CI 1.54 to 2.33) and 1.05% per day (95% CI 0.95 to 1.15) respectively in patients with G6PD deficiency and normal patients; a mean reduction of 1.3% per day was observed among patients who received AQ+SP regardless of G6PD status (95% CI 1.25 to 1.45). Patients with G6PD deficiency recipients of CD+A had significantly lower haematocrit than the other groups until day 7 (p = 0.04). In total, 10 patients had severe post-treatment haemolysis requiring blood transfusion. Patients with G6PD deficiency showed a higher risk of severe anaemia following treatment with CD+A (RR = 10.2; 95% CI 1.8 to 59.3) or AQ+SP (RR = 5.6; 95% CI 1.0 to 32.7).

CONCLUSIONS

CD+A showed a poor safety profile in individuals with G6PD deficiency most likely as a result of dapsone induced haemolysis. Screening for G6PD deficiency before drug administration of potentially pro-oxidants drugs, like dapsone-containing combinations, although seldom available, is necessary.

Antimalarial drugs in pregnancy: a review

In this review we examine the available information on the safety of antimalarials in pregnancy, from both animal and human studies. The antimalarials that can be used in pregnancy include (1) chloroquine, (2) amodiaquine, (3) quinine, (4) azithromycin, (5) sulfadoxine-pyrimethamine, (6) mefloquine, (7) dapsone-chlorproguanil, (8) artemisinin derivatives, (9) atovaquone-proguanil and (10) lumefantrine. Antimalarial drugs that should not be used in pregnancy including (1) halofantrine, (2) tetracycline/doxycycline, and (3) primaquine. There are few studies in humans on the pharmacokinetics, safety and efficacy of antimalarials in pregnancy. This is because pregnant women are systematically excluded from clinical trials. The absence of adequate safety data, especially in the first trimester, is an important obstacle to developing treatment strategies. The pharmacokinetics of most antimalarial drugs are also modified in pregnancy and dosages will need to be adapted. Other factors, including HIV status, drug interactions with antiretrovirals, the influence of haematinics and host genetic polymorphisms may influence safety and efficacy. For these reasons there is an urgent need to assess the safety and efficacy of antimalarial treatments in pregnancy, including artemisinin based combination therapies.

World Antimalarial Resistance Network I: clinical efficacy of antimalarial drugs

The proliferation of antimalarial drug trials in the last ten years provides the opportunity to launch a concerted global surveillance effort to monitor antimalarial drug efficacy. The diversity of clinical study designs and analytical methods undermines the current ability to achieve this. The proposed World Antimalarial Resistance Network (WARN) aims to establish a comprehensive clinical database from which standardised estimates of antimalarial efficacy can be derived and monitored over time from diverse geographical and endemic regions. The emphasis of this initiative is on five key variables which define the therapeutic response. Ensuring that these data are collected at the individual patient level in a consistent format will facilitate better data management and analytical practices, and ensure that clinical data can be readily collated and made amenable for pooled analyses. Such an approach, if widely adopted will permit accurate and timely recognition of trends in drug efficacy. This will guide not only appropriate interventions to deal with established multidrug resistant strains of malaria, but also facilitate prompt action when new strains of drug resistant plasmodia first emerge. A comprehensive global database incorporating the key determinants of the clinical response with in vitro, molecular and pharmacokinetic parameters will bring together relevant data on host, drug and parasite factors that are fundamental contributors to treatment efficacy. This resource will help guide rational drug policies that optimize antimalarial drug use, in the hope that the emergence and spread of resistance to new drugs can be, if not prevented, at least delayed.

Can malaria be controlled where basic health services are not used?

OBJECTIVE

To assess the potential of integrating malaria control interventions in underused health services.

METHODS

Using the Piot predictive model, we estimated malaria cure rates by deriving parameters influencing treatment at home and in health facilities from the best-performing African malaria programmes and applying them to Yanfolila district, Mali.

RESULTS

Without any malaria control intervention, the population cure rate is 8.4% with home treatment, but would be 13% if access to timely treatment were improved (as in Kenya). A further 3.2% of malaria patients could be cured in institutional settings with more sensitive diagnosis, timely start of treatment, better compliance (as in Uganda, Tanzania, Ghana) and 80% chloroquine efficacy. Applied in a setting where 7.6% of malaria patients seek institutional care, these assumptions would result in a total population cure rate of 14.5%. Increasing the health service user rate from 0.17 in Yanfolila to 0.95 new cases/inhabitant/year (as in Namibia) would result in half of all malaria patients attending professional services, raising the cure rate to 26.1%.

CONCLUSION

If malaria patients are to be treated and followed-up early and appropriately, basic health services need to deliver integrated care and be attended by an adequate pool of users. Improved service user rates and case management can increase malaria cure rates far more than isolated control interventions can. This has implications for international policies endorsing a narrow disease-based approach.